Coupling devices for use in offshore well work



June 24, 1969 w. RPQSTLEWAITE I 9 I COUPLING DEVICES FOR USE IN OFFSHORE WELL WORK Filed Maya, 1966 v Sheet 1 of 4 v P I e .1 7 g 5*e 4ss as f INVENTOR WILLIAM R. POSTLEWA/TE June 24, 1969 w. R. POSTLEWAITE COUPLING DEVICES FOR USE IN OFFSHORE WELL WORK Filed May 2, 1966 A $5 H V INVENTOR WILL/AM R. POSTLEWA/TE W. R. POSTLEWAITE June 24, 1969 COUPLING DEVICES FOR USE IN OFFSHORE WELL WORK Filed May 2, 196? Sheet lNV ENTOR WILLIAM R. POSTLEWA/TE A ORNEYS June 24, 1969 w, R. POSTLEWIAITE 3,451,699

COUPLlNG DEVICES FOR USE IN OFFSHORE WELL WORK Filed May 2, 19m Sheet 4 of 4 INVENTOR W/LL/AM R. POSTLEWA/TE BY gu-fivu U n v I United States Patent 3,451,699 COUPLING DEVICES FOR USE IN OFFSHORE WELL WORK William R. Postlewaite, Menlo Park, Calif., assignor to Chevron Research Company, San Francisco, Calif., a

corporation of Delaware Filed May 2, 1966, Ser. No. 546,821 Int. Cl. F16b 7/00 US. Cl. 287-87 Claims ABSTRACT OF THE DISCLOSURE Coupling devices useful in offshore well work for connecting a guide line to a guide post, which coupling devices incorporate means allowing for separation of the guide line from the guide post when the lateral force applied on the guide post by the guide line exceeds a predeterminable amount.

This invention relates to coupling means for connecting guide lines to underwater guide posts; and, more particularly, this invention relates to coupling devices useful to connect guide lines to guide posts, which devices include means for limiting the lateral load that can be exerted on the guide posts.

In deep water wall drilling and well completion, it is now customary to install guide posts around a well. The tall guide posts stand upright and are used to guide heavy equipment to a precise location at the well site. The guide posts are relatively rigid and are usually from to 20 feet or more in height. Guide cables are connected to the upper ends of the guide posts and extend to a surface vessel or the like. The guide cables are used to guide apparatus from the ship to the guide posts. If the surface vessel moves from a position substantially above the well site, an excessive lateral strain can be put on the posts. If the guide posts are bent or otherwise damaged by the lateral force, it may mean loss of the well since it may not be possible to get equipment back on the Well.

It is, therefore, a particular object of this invention to provide coupling means for connecting a guide line to a guide post, which coupling means includes load-limiting means for limiting the lateral load on a guide post to an acceptable safe level.

Briefly, the present invention relates to coupling devices useful in offshore well work for connecting a guide line to a guide post. The coupling device connects the guide line to the guide post and incorporates means allowing for separation of the guide line from the guide post when the lateral force applied on the guide post by the guide line exceeds a predeterminable amount. Thus the coupling device of the present invention is useful to prevent bending of the guide post by lateral force applied through the guide cable.

In a broad aspect, the present invention provides apparatus for use underwater comprising a guide post having an upper end, a guide cable and coupling means for coupling said guide cable to the end of said guide post, said coupling means including means for limiting the lateral force that can be applied to said guide post by said guide cable.

Further objects and advantages of the present invention will become apparent from the following detailed description read in light of the accompanying drawings which are a part of this specification, and in which:

FIGURE 1 illustrates, in side elevation with parts broken away for clarity, apparatus assembled in accordance with this invention;

FIGURE 1A is a schematic view of a portion of th apparatus of the invention and illustrates the forces acting on the coupling member;

FIGURE 2 is an elevational view, partially in section, illustrating the preferred embodiment of the present invention;

FIGURE 3 is an enlarged sectional view of a portion of the apparatus illustrated in FIGURE 2 and more clearly shows features of the present invention;

FIGURE 4 is section 4-4 of FIGURE 2;

FIGURE 5 is section 5-5 of FIGURE 2;

FIGURE 6 illustrates, in side elevation with parts broken away for clarity, an alternative embodiment of the present invention;

FIGURE 7 is a sectional view taken at line 77 of FIGURE 6;

FIGURE 8 illustrates, in side elevation with parts broken away for clarity, still another alternative embodiment of the present invention;

FIGURE 9 is a sectional view taken at line 99 of FIGURE 8; and

FIGURE 10 is a sectional view taken at line Ill-10 of FIGURE 8.

Referring to the drawings and particularly to FIG- URE 1, there is illustrated an offshore drilling vessel, generally designated by the numeral 30, which has been anchored by lines 432 and 433 over a body of water 33 in approximate vertical relationship over the site where a well has been drilled in the underwater bottom 34. The drilling vessel 30 has an operational base, which is generally indicated by the numeral 300. The operational base 300 of the vessel 30 is suitably maintained to run drill pipe, handle cables, and to perform other functions that are well known in the underwater drilling and well completion art. A permanent base, generally designated by the numeral 36, islocated at the subsea well site and forms part of the fixed well site apparatus. The permanent base in this instance includes .a pair of guide posts 452 and 453. Flexible guide lines 455 and 456 are connected between the operational base 300 of the vessel 30 and the upper ends of guide posts 452 and 453 respectively.

The guide posts 452 and 453 are tall, rigid posts useful to guide apparatus to specific locations on the well control apparatus. If the drilling 'vessel for some reason, such as a storm, moves off from over the well site with the guide cables still attached, the cables could come to a position indicated in phantom in FIGURE 1. The guide cables are necessarily strong, steel ropes. Therefore, the potential force which would be exerted on the guide posts by the drilling vessel is very large; i.e., being on the order of 40,000 to 50,000 pounds. If even a substantial portion of such a force is applied laterally on the guide posts, bending of the posts can result. If such bending occurs, it may not be possible to come back onto the well. Attempts to straighten or to replace the posts are costly and not necessarily successful, and loss of the well could result. For this reason, coupling devices 40 and 50 are provided to connect the guide cables to the guide posts, which devices limit the lateral pull that can be applied to the posts by the guide cables.

In accordance with the invention then, the coupling device automatically limits the maximum horizontal load component that an inclined guide cable can exert on a guide post. A breaking link is incorporated into the coupling device, which breaking link has a tensile strength of less than the tensile strength of the guide line. In normal operating conditions, it is desirable that the force required to part the breaking link be equal to the tensile strength of the breaking link through a small rope angle with the vertical. This angle is illustrated as 0 in FIG- URE 1. Once the normal working range of this angle has been exceeded, however, it is desirable to arrange for parting of the breaking link by a substantially smaller horizontal component of force. Thus under normal operating conditions, the coupling device is arranged to permit the guide cable an ample practical working range of from to to degrees throughout which the tensile strength of the breaking link alone limits the maximum horizontal component of the cable pull. Once, however, the larger allowable angle of deviation from the vertical is exceeded, then the coupling device will separate when a horizontal component of force of a much less magnitude occurs. This load-limiting feature is accomplished by the particular geometric relationships and portions of the component coupler parts.

FIGURE 1A illustrates the forces acting on a coupling member. The upper portion 340 of the coupling member is connected to the top of a post 352 in a manner so as to allow universal motion between the upper portion and the post through a limited angle with the vertical. A breaking link L connects the member 340 to the top of the post 352. The strength of the breaking link is the load-limiting factor through an angle 0 with the vertical. Thus the force P required to break the breaking link within angle 0 is equal to the breaking stress of the link L. When the angle of the guide line force P exceeds the limiting angle 9, the post top and the shoulder of member 340 meet, such as at A. The lever arm thus formed provides a load amplification on the breaking link L. The geometric relationship between the vertical dimension x of member 340 and the horizontal component a of the member 340 is selected so that the maximum horizontal component H required to separate link L is below a predetermined maximum allowable load. A preferred range of ratios of x to a is between 2 /2 to 1 and 8 to 1. Ratios of between about 5 /2 to 1 and 6 /2 to 1 have been found to be particularly useful.

As noted above, for rope angles ranging from the vertical to 0, the rope pull P is axial to link L. The angle 0 is chosen as a limiting angle to provide a permissible maximum horizontal component H for which the guide post can be safely designed to withstand. In a typical situation where the guide rope has a breaking strength of from 45,000 to 50,000 pounds, a breaking link L with a 33,000 pound ultimate load is suitable. A ten degree maximum value for 0 also is suitable under most operating conditions. With a breaking link L of 33,000 pounds, the post top value of horizontal force H can be adjusted by proportioning the x/a ratio. The H component needed to fail link L is found from the relationship H: [P(sin e) ]x=La. For example, with an x/a ratio of 5.76, the H component needed to separate a 33,000 pound link is equal to 5,720. For an x/a ratio of 6.6,- the H component needed to break link L is 5,000 pounds.

Referring to FIGURES 2-5, a preferred embodiment of apparatus assembled in accordance with the present invention will now be described in detail. A coupling device, generally designated by the numeral 40, is used to connect a guide post, for example guide post 452, to a guide cable, for example guide cable 455. It is preferred that the coupling device 40 be disconnectably connected to the guide post 452. The coupling device 40 may then be removed in a conventional manner with the guide cable 455. However, the connection between the coupling device 40 and the top of the guide post 452 may take any convenient form. For example, as illustrated in FIGURE 2, the upper portion of the guide post 452 is provided with a suitable annularly extending groove 460 having beveled shoulders 461 and 462. A member 470 of the coupling device is provided with suitable holes for locking dogs 463 which are mateable with the annular groove 460. A sliding sleeve 464 is provided with an annular recess 465 which is alignable with the locking dogs 463 to permit the locking dogs to retreat out of annular groove 460 and to thus disconnect the members. When the coupling device is in position on the post, the

sliding sleeve is held in the engaged position so that the sleeve forces the locking dogs inward into the annular groove 460. The sleeve is normally maintained in this position by means of suitable springs 466. When it is desired to release the connection, a sinking bar (not shown) is placed over cable 455 and dropped onto the upper portion of the coupling device. The sinking bar is provided with suitable fingers for inserting through holes 106, 107, 108 and 109 in the upper cap member 105 to depress sleeve 464 and allow the locking dogs to retreat outward into the annular groove 465. The sinking bar is aligned in position on the coupling device by means of camming lugs 470, 471, 472 and 473. Thus as long as the force applied on the guide post by the guide line is in a vertical or near vertical direction, the coupling device of the present invention functions in a conventional manner.

As described above, the lower stationary portion of the coupling device functions in a known manner to disconnectably connect the guide line to the guide post. The present invention is particularly concerned with the lateral load-limiting means incorporated into the coupling device. Thus in accordance with the invention, the guide cable 455 is connected by suitable means to the upper end of a breaking link 120. For example, the guide cable 455 is conveniently connected to member 130 by means of fitting 131. The member 130 is connected in turn to an upper spherical member 132 which is' positioned in a spherical recess in the upper cap member 105. The spherical member 132 has a downwardly extending portion 133 which has threads cut into its lower end. The upper spherical member 132 is held in position by means of a threaded insert 134.

A lower spherical member 140 is held in position in the lower portion of the coupling member 40 by threaded insert 141. The lower spherical member 140 has an up wardly extending sleeve 143 which slidingly engages over the downwardly extending portion 133 of the upper spherical member. The lower spherical member has a passageway through its center to accommodate breaking link 120. Thus the coupling member is made up of a lower stationary section and an upper movable section held together by a breaking link which may be sized in accordance with the requirements for a specific application. This assures that only axial forces can be applied to breaking link 120 so that it will fail under tension in a predictable manner.

FIGURE 3 shows the position of the coupling device when the direction of pull of the guide cable exceeds an allowable angle with the vertical. The outer sleeve of the lower stationary portion of the coupling device has a shoulder 101 and a spherical guide bearing neck portion 102. The upper movable cap member 105 of the coupling device has a lower shoulder 206. When the direction of pull exceeds a predeterminable angle, the two corresponding shoulders 101 and 206 meet, as shown by the numeral in FIGURE 3, to establish a fulcrum point. By selecting the length of the lever arm and the untimate strength of the breaking link, the maximum lateral pull H that can be exerted on the guide post by the guide cable can be adjusted to any desirable value.

After a rupture of the breaking link has occurred, the upper movable portion 105 of the coupling member is free to go with the guide cable 455. The lower stationary portion of the coupling device remains connected to the top of guide post 452. A stilf spring 113 and piston member 114 are provided beneath the lower spherical member to urge the spherical member into a position so that extension 143 returns to a vertical position. This is done to prevent fouling on the extension when subsequently coming back onto the guide post to remove the lower stationary portion of the coupling device so that a new coupling member and guide Cable can be attached.

With reference to FIGURES 6 and 7, an alternative embodiment of apparatus assembled in accordance with the present invention will be described in detail. A coupling device, generally indicated by the numeral 70, is used to connect a guide cable 71 to a guide post 72. The connection between the lower stationary portion of the coupling member and the guide post is made in a conventionally known manner by means of a spring latch coupler, which couple includes spring 73 and latch member 74 which slides in keyway 75. The spring latch member is connected and disconnected from the guide post utilizing known means.

The coupling device is made up of two major parts; the lower stationary portion and the upper movable portion. The stationary portion of the coupling device includes outer sleeve 76 and inner sleeve 77. A chamber for a spherical member is provided by means of housings 78 and 79 which are secured to the stationary portion by suitable connecting means. A breaking link 80 is connected between a pair of spherical members 81 and 82 by means of suitably overlapping telescopic sleeves 83 and '84.

The upper spherical member 82 is contained in a recess in upper cap member 85 and retained there by means of threaded insert 86. The upper cap member is connected to cable 71 by means of collar 87 having ball 88 which is captured on the upper cap member by means of fitting 89. The fit between upper cap member 85 and insert 78 of the stationary portion of the coupling device is such that the guide line is allowed free movement through a predetermined angle before the corresponding shoulders of the two pieces meet and form a pivot point. Thus as illustrated in phantom, the directional pull of the guide line may normally deviate somewhat from the vertical before bringing into play the leverage system which will reduce the amount of lateral force needed to part breaking link 80.

An additional feature of this embodiment of the invention is the provision of an outer tubular sleeve 90 which assists in preventing damage to or inadvertent tripping of the coupling device. A flexible rubber sleeve 91 is also provided around the corresponding shoulders of the upper cap member 85 and insert 78 to prevent foreign particles from becoming lodged in the opening between the shoulders and thus changing the leverage point.

With regard now to FIGURES 8-10, inclusive, another alternative embodiment of the present invention will now be described in detail. The lower stationary portion of the coupling device used to couple the guide line to the guide post in this embodiment is generally similar to the lower portion of the coupling device used in the preferred embodiment illustrated in FIGURE 2; and, for the sake of convenience, similar numbers will be used to describe similar parts of the embodiments. Thus the coupling device attaches to the top of a guide post 452 by means of locking dogs 463 contacting annular groove 460. An outer member 100 cooperates with an inner member 470 to form an annular chamber in which a sliding sleeve 464 may move. The sliding sleeve 464 engages with the rearward portion of the locking dogs and, depending on the position of the sleeve 464, either urges the dogs 463 into annular groove 460 or allows the, dogs 463 to retreat out of the annular groove 460. Spring member 466 urges the sliding sleeve upwardly into a position which, as shown in FIGURE 8, forces the locking dogs into a position which disconnectably connects the coupling device to the guide post.

The upper movable portion of the coupling device is connected to the lower portion by means of a universal joint formed of U-shaped members 501 and 502. One of "the U-shaped members 501 is fixedly connected to the lower stationary portion while the other interlinked U- shaped member is arranged 90 out of phase and fixedly connected to the upper movable portion of the coupling member. The guide cable 571 is connected to the upper movable portion by suitable means, such as collar 587, extension 590, braking link insert 591 and cap member 592. In this particular embodiment, the breaking link is not an essential element to limit lateral force and is used only to limit the maximum force applied by the cable. In the event that an excessive force does cause breaking link 591 to part the movable portion of the coupling device which remains connected to the post is retained in an upright position by means of resilient member 530 acting on extension arm 531. Thus guide cable failure is avoided and so prevents the tangling of hundreds of feet of wire cable around the Christmas tree.

The upper movable portion of the coupling device is provided with downwardly projecting shoulders 550-554. One of more of these shoulders contact the upper end of sliding sleeve 464 when the direction of pull of guide cable 571 exceeds a predeterminable angle. If the angle increases, the shoulders depress sliding sleeve to a position where the locking dogs are cammed out of groove 460; and thus the guide line is released from the post.

I claim:

1. A coupling device for use in underwater wells for connecting a guide line to a guide post and for limiting the lateral stress that can be exerted on said guide post by said guide line comprising a guide post located beneath a body of water, a first member on said guide post, a second member, vessel means positioned in said body of water above said guide post, a guide line extending from said vessel means, means for connecting said second member to said guide line, connecting means for connecting said first member and said second member together and separating means allowing for separation of said members when the lateral force applied on said guide post by said guide line exceeds a predeterminable amount, said separating means including force amplification means for amplifying the lateral force applied by said guide line.

2. A coupling device for use in underwater well work for connecting a guide line to a guide post and for limiting the lateral stress that can be exerted on said guide post by said guide line comprising a guide post located underwater, a first member, means for attaching said first member to said guide post, a second member, a vessel means in the water above said guide post, a guide line extending from said vessel means, means for connecting said second member to said guide line, connecting means for connecting said first member and said second member together, said connecting means permitting universal movement between said members through a limited angle with the vertical and separable disconnect means becoming operative with said last mentioned connecting means to absorb and amplify lateral force of the guide line upon the assumption of said limited angle and releasing the connection between said members when the lateral force applied on said guide post by said guide line exceeds a predeterminable amount.

3. Apparatus for connecting a guide line to a guide post comprising a guide post, a lower member having an upper shoulder, means for connecting said lower member to said guide post, an upper member having a lower shoulder contactable with the upper shoulder of said lower member, a guide cable means for connecting said guide cable to said upper member, breaking link means connecting said lower member and said upper member and means allowing for universal movement between said lower member and said upper member, said universal movement being limited by contact between said upper and lower shoulders whereby the lateral force on said breaking link is amplified by the resulting lever arm formed by one of said members.

4. Apparatus of claim 3 where the member forming the lever arm has a vertical dimension x and a horizontal dimension a and the ratio of x to a is between 2 /2 to 1 and 8 to 1.

'5. Apparatus of claim 3 further characterized in that the lever arm has a vertical dimension x and a horizontal dimension a and the ratio of x to a is between 5 /2 to 1 and 6 /2 to 1.

References Cited UNITED STATES PATENTS 2,909,359 10/1959 Bauer et a1 175-7 10 3,197,552 7/1965 Flair 28786 X CARL W. TOMLIN, Primary Examiner.

A. V. KUNDRAT, Assistant Examiner.

US. Cl. X.R. 1757 

